The present disclosure relates to an onboard apparatus control system including a portable apparatus carried by a user and an in-vehicle apparatus mounted in a vehicle to control an onboard apparatus according to the position of the portable apparatus.
A known apparatus transmits a verification radio wave from each of multiple transmitting antennae installed in several places of a vehicle. By receiving a response radio wave which a portable apparatus carried by a user transmits upon receipt of the verification radio wave, the apparatus performs verification and position determination of the portable apparatus, thereby performing locking control, unlocking control etc. of a door of the vehicle according to the position of the portable apparatus (for example, refer to JP-2004-84406A).
The apparatus disclosed in JP-2004-84406A transmits a request signal from multiple transmitting antennae installed in a center pillar of a vehicle on a driver seat side, in a center pillar on a front passenger seat side and in a trunk room etc. A portable apparatus transmits a response signal in response to the request signal. Accordingly, the apparatus determines the position of the portable apparatus based on the response signal. In this way, by transmitting the request signal from the multiple transmitting antennae, the apparatus can determine the position of the portable apparatus with a certain degree of accuracy. However, concurrently transmitting the radio waves from the multiple transmitting antennae may lead to interference, making it difficult for the portable apparatus to receive respective radio waves. For this reason, it is necessary to sequentially transmit the radio waves from the antenna by shifting transmission time, and as a result, it takes a long time to determine the position of the portable apparatus.